System of motor control



June 25, 1929.

H. HAEHLE ET AL SYSTEM OF uo'roR CGNTROL 2 Sheets-Sheet Filed Sept 20. 1924 INVENTORJ, Ham/m 1945/11.: ma STEVE K/MY/Y/GK A TTORNEYJ.

June 25, 1929. H. HAEHLE ET AL 1.718.232

SYSTEM OF MOTOR CONTROL Filed Sept. 20, 1924 2 Sheets-Sheet 2 'ATTORNEYJI Patented June 25, 1929.

:UNITED STATES PATENT OFFICE.

HERMAN KAEHLE, O1 MILWAUKEE, AND STEVE KBAYNIOK, OF WEST LLLIS, WIS- CONSIN, ASBIGNOBS TO HABNISCHFEGEB CORPORATION, OF MILWAUKEE, WISCON- SIN, A CORPORATION OF WISCONSIN.

SYSTEH MOTOR CONTROL.

Application filed September 20, 1924. Serial No. 738,813.

This invention relates to an improved method of and apparatus for controlling direct current crane and hoist motors and has for one of its objects to provide means for increasing the lowering speed when the loads on the hook of the crane or hoist are light.

In Letters Patent No. 1,293,112, granted February 4, 1919 to Pawling & Harnischcontacts, a circuit is established causing the motor to revolve in such a direction that the load will be hoisted. When the fingers are brought into contact with the other set of segments, a dynamic braking circuit is established and the motor connections are then such that the motor will revolve in a direction to lower the load.

This dynamic braking connection of the atore-mentioned patent comprises two circuits, one circuit containing the series field coil. the series wound coil of a solenoid brake, and a resistance; and the other circuit containing the armature and a resistance. To lower the empty hook of the crane or hoist requires a certain amount of power in order to overcome the friction in the gearing and bearings and the'motor armature will draw a certain amount of current. If, however, the load to be lowered is sufiicient to overhaul the motor, the armature will speed up until finally it will begin to generate current and thus cause the motor to operate as a generator. The heavier the load on the hook the higher will be the armature speed and the greater the current generated.

Thus, we have the condition where a heavy load is lowered at a higher speed than. a

light load. Obviously this is not a desirable condition. The ideal system is one in which a light load. may be lowered quickly and a heavy load at a slower speed and while such systems have heretofore been designed they have proved in actual practice to possess certain objectionable features. One such system, for instance, depends upon the interaction of two relays which must operate at certain'relative speeds in order to function properly. It has been found that after the parts have become slightly worn or corroded or otherwise hampered by the accumulation of 011, dust or grit, for instance, the opera.- tion thereof is'..uncertainand the do not function properly or accurately, t e entire apparatus being thus rendered, to a certain extent, unreliable over long periods of use.

Furthermore, the system above referred to consists in regulating the speed of the reverse movement of the motor as in the lowermg operation by the quantity of current required for a preceding direct or hoisting movement of the motor. 1 i V One of the objects of the present inventionis to provide an improved method of and apparatus for controlling an electric motor of the type described which shall overcome the various objections .and disadvantages above pointed out, and further to provide a control wherein the lowering speed of the motor may be made directly dependent upon the weight of the load being lowered and controllable by said weight.

A further object of the invention is to simplify and improve generally prior motor controls of the character named.

Other objects and advantages will be ap parent from the following description taken in connection with the accompanying drawings wherein the invention is diagrammatically illustrated.

In the drawings Fig. 1 shows a general wiring diagram of the system, and

Figs. 2, 3 and 4 illustrate simplified wiring diagrams of certain portions of the apparatus with the controller in certain positions.

Referring more in detail to the drawings and particularly to Fig. 1 thereof, the controller fingers are indicated by the circles 5 to 20, inclusive, and the contact segments on the lowering side of the controller bear reference characters 33 to 47, inclusive.

The hoisting side of the controller is identical with the hoisting side shown in Patent No. 1,293,112 above mentioned, and will not, therefore, require further description herein.

The contact segments 33 to 47, inclusive, on the lowering side of the controller are disposed in the same manner as indicated in the previously mentioned patent. In addition to these segments, however, two segcontact with point 31.

No. 81 is a two pole contactor comprising armature 51, pivoted at 52 and energizing coil 53 and resistance 54.

If the coil 53 is energized, the armature 51 will make contact with points '49 and 50. No. 2 represents the armature of the motor.

- No. 3 is the series field. No.4 is a series wound brake coil. 21 and 22 are resistances and 79 is a resistance connected across points 85 and 28.

Assuming now that the fingers of the controller are moved to the position 56 on the lowering side of the controller, the circuit will be established from the positive through the knife switch 1 to'finger 6, segment 34, connecting bar 67 ,seigment 33 finger 5, wire 82 and through series coil 32 to point 83. From here the circuit divides, one part flowing through field 3, brake 4, wire 84 and through blade 26 to oint 28, thence through Wire 86, finger 10, t rough resistances 71 to 77, to finger 18, thence to segment 45 and through connecting bar 69 to segment 46.

Another part of the currentwill flow from point 83 through armature 2, wire 87, res1st-' ances 22 and21, wire 88, to finger 20, segment 47 and connecting bar 69 to segment 46 where it will meet the firstpart of the current.

From here the current will flow through finger 19 and wire 91, through knife switch 1 to the negative. 7

An additional circuit is established from point 92 between resistances 21 and 22 through wire 89 to finger 9, segment 36, connecting bar 68, segment 37 to finger 10, where this current will meet the first current described.

As the current flows through the coil 32 the plunger 48 will be magnetized and will raise the arm 30 thereby interrupting contact between 30 and 31. An additional circuit is also established through finger 6, segment 34, connecting bar 67, segment 64, finger 66 and through wire 94 to point 52 of the double pole contactor 81. From here the current flows through resistance 54, coil 53 and through wires 95 and 91 to the negative. Coil 53 is now energized and will exert a pull on armature 51, thus bringing the armature in contact with points 49 and50. The closing of this contactor establishes a further circuit from 52 through 51 and 50 and wire 97 to coil 24 and to finger 70. However, this fore the circuit is still open.

The cireuitobtained on the first lowering notch 56 is also shownin the simplified diagram of Fig. 2. It will be noticed that the current flows from the positive side of the controller through the coil 32 to point 83 where the current divides, one part flowing through 3, 4, 26, 71to 77 to the negative of the controller while the other partof the current flows from the armature 2 and resistances 22 and 21 to the negative.

A dynamic braking circuit is therefore established in the same way as in the aforementioned patent. The plunger of the relay has been'lifted and has interrupted contact between 30' and 31.

The double pole contactor is closed but the single pole contactor 26 has not yet been affected. Resistance 79 is still short circuited by the contactor'26.'

If the fingers'are moved to the next lowering position 57, the circuit which started at finger 66 is now interrupted.

However, the coil 53 is still energized from point 93 on relay 80 through wire 96 to point- 49, armature 51, point 52 and through resistance 54 and coil 53, wires 95 and 91 to the negative.

Therefore this double pole contactor will remain closed even after finger 66 has leftsegment 64.

If now the fingers are moved to the last lowering position 63 on the controller the circuit previously described through coil 24"foa will be closed through finger 70, segment 65, bar 69, segment 46, finger 19 and through wire 91 to the negative.

The coil 24 will now be energized and will attract armature 27 against the pull of thus be opened.

This condition is shown in simplified diagram of Fig. 3. a

It will be noted by referring to Fig. 3 that the current will now flow from the positive side of the controller through coil 32, point 83 and thence divide as described before.

However, contactor 26 is now opened and therefore the current flowing through field 3 and brake 4 will have to flow through resistance 79 and thence through resistances 71 10 spring 29 and contact between 26 and 28 will armature in the oppositedirection.

the book is heavy, this will tend to overhaul the motor and the armature will begin to generate current.

Then the current will flow through the This condition is shown in diagram of Fig. 4.

The armature now supplies a certain part c of the total current required by the system so that the current drawn from the supply lines will diminish.

Therefore, the current flowing from the positive side of the controller through series coil 32 on-the relay will now diminish. The proportions of this relay are selected in such a way that when the current is dropped to a certain value, plunger 48 on the relay will drop and thereby establish contact between 30 and 31.

------ When this contact is established, the-coil circuit.

53 of contactor 81 will be by-passed through wire 197, contacts 30 and 31 and wire 98.

The current will therefore stop flowing through 53 and contactor 81 will open. As this contactor opens the current through coil 24 of the contactor 78 will be broken and the arm of lever 26 will close against contact 28 under the influence of spring 29. The resistance 7 9 will-therefore be short-circuited again by contact arm lever 26, thus reducing the total amount of resistance in the field The current in this circuit will therefore increase and thus prevent excessive speed of the motor. This condition is shown in Fig. 4.

It is therefore seen that the relay controls the contactor 81, which in turn, in connection with the contacts 6570, controls contactor 78. The proportions of relay 80 are such that with a light load on the hook the contactor 78 will open and insert resistance 79 into the field circuit, while with a heavy load on the hookthe contactor 78 will remain closed, thus leaving resistance 79 short-circuited.

The motor is illustrated in the drawings as series wound, but as will be readily understood by those skilled in the art, it may, if desired, be of the compound wound type. It will also be obvious that the present improvements are susceptible to many other changes and modifications without departing from the spirit of the invention, and it is not therefore desired to limit .or restrict the same to the particular form or embodiment herein illustrated, except where limitations may appear in the appended claims.

We claim:

1. The method of controlling an electric motor which consists in connecting the mo tor armature in series with a resistance, inserting a short-circuited resistance in the motor field circuit, connecting the motor field circuit in parallel with the armature-resistance circuit, connecting said parallel circuits across the supply lines through parallel sistances in series with the motor field circuit, then removing the short circuit connection from the resistance first inserted in the field circuit, and rendering said short circuit connection automatically operable in response to motor load current.

2. The method of controlling an electric motor which consists in inserting a resistance in the motor field circuit, establishing a short circuit connection for said resistance, connecting the motor field circuit and the motor armature circuit in parallel across the supply lines through a second resistance, placing said second resistance in the motor field circuit, and then breaking and making the short circuit connection automatically in response to motor load current.

3. A system of motor control comprising two parallel circuits, the first circuit containing the field of the motor anda resistance the second circuit containing the armature and a second resistance, a third resistance connected in the first circuit, a contactor arranged to short circuit said third resistance and a relay responsive to motor load current-connected in the supply line to the motor arranged to release said contactor to short circuiting position if the motor load current in said relay drops below a certain value.

4. A system of motor control including two circuits, one circuit containing the motor field, the second circuit containing the motor armature, a resistance connected in the first circuit, a contactor adapted to shortcircuit said resistance, and a relay responsive to motor load current connected in the supply line to the motor arranged to release the contactor to short-circuiting position if the motor load current in said relaydrops below a certain value.

5. A system of motor control comprising two parallel circuits, the first circuit containing the field of the motor and a resistance, the second circuit containing the armature of the motor and a second resistance, a third resistance inserted between said two parallel circuits and the supply line, a movable connection for placing said last mentioned resistance in series with the motor field circuit, a short circuit connection for the first mentioned resistance, said connection including a magnetically operated contactor adapted to. make and break said short circuit connection, and a relay controlling said contactor, said relay being responsive to motor load current and being connected in the supply line and arranged to release the contactor to close the shortcireuit connection when the motor load current falls below a predetermined value.

6. A system for controlling hoist motors comprising field and armature circuitsfor the motor, a main controller for operatively arranged to be connected to the supply lines by movement of the main controller from ofi position to lowering position, and a second contact-or arranged to close the break in the solenoid energizing circuit simultaneously with the movement of the main controller to first lowering position.

7. A system -for controlling hoist motors comprising field and armature circuits for the motor, a main controller for operatively connecting the motor to suitable supply lines through said circuits, said field circuit in eluding a resistance, a contactor short circuiting said resistance, a solenoid for operating thecontactor, and means for energizing and de-energizing said solenoid including a normally broken solenoid energizing circuit arranged to be connected to one of the supply lines by movement of the main controller from of position to lowering position and a second contactor arranged to close the break in the solenoid energizing circuit simultaneously with the movement of the main controller to first lowering position, and means to complete the solenoid energizing circuit when the main controller is moved to full lowering position whereby to operate the first mentioned contactor to remove the short circuit fromthe I field resistce.

8.. The system described in claim 6 wherein a solenoid is provided to operate the sec- .ond mentioned contactor, a control c1rcu1t for said solenoid, said eircuitincluding a relay responsive to motor load currentand ar- 7 ranged'to release the second mentioned contactor to open position when the motor load current falls below a predetermined value whereby to cause said first mentioned contactor to return to a short circuiting position.

9. The system described in claim 6 wherein a solenoid is provided for operating the second mentioned contactor and a control a circuit for said solenoid including a contact arranged for connection to the su ply lines by movement of the main contro or to the first lowering position.

10. The system described in claimfi wherein a solenoid is provided for operating the second mentioned contaetor and a control circuit for said solenoid including contacts erred for connection to the supply lines atlases by the movement of. the main controller to the first loweringposition, said solenoid circult also including a shunt circuit around the solenoid winding, said shunt circuit being provided with a solenoid operated switch, said last mentioned solenoid being arranged in themain motor circuit and responsive to motor load current to close the shunt circuit to short circuit the solenoid of said second mentioned contactor when the motor load current falls below a predetermined value.

11. A system of motor control including a controller and two parallel circuits, the first circuit containing the motor field and a plurality of resistances, the second circuit containing the motor armature and another resistance, a contactor adapted to short circuit one of the resistances in the first mentioned circuit, control means for said contactor inclhding a second cont-actor, switch means contained in the controller for energizing the second contactor to close the circuit through the control means of the first mentioned contactor to move the same from short circuiting position, and a relay connected into the supply line of they motor enda ranged to open said second mentioned contactor if the current through said rela drops below a predetermined value. 12. In a motor control system, the combination with an electric motor and a controller for operatively connecting the same to suitable supply lines and including a resistance, of means including a relay having an actuating coil in series with the mainline of the motor for maintaining said resistance shortcircuited during the starting period of the motor, and placing said resistance in series with the field winding simultaneously with the movement oi the controller'to full running position.

13. In a motor control system, the combination with an electric motor and a controller for operatively connecting the same I to suitable supply lines and including a resistance, of means including a relay having an actuating coil in series with the main line of the motor for maintaining said resistance short circuited during the starting period of the motor, placing said resistance in series with the field winding simultaneously with the movement of the controller to full running position, and short circuiting said resistance when the motor load current falls below a predetermined value.

In witness whereof we have hereto afiixed our signatures.

HERMAN HAEHLE. STEVE KRAYNICK. 

